Senior bearded dragon lighting advice at age 7

Bad lighting is the single most common husbandry mistake with bearded dragons — incorrect UVB or basking temperatures cause metabolic bone disease and chronic illness that many owners don't recognise until serious damage is already done. At seven years old your dragon is firmly in senior territory, and a slowdown can absolutely be lighting-related rather than just age. Before I can give you a useful answer, can you tell me: what size enclosure are they in, what UVB and basking bulbs are you currently using (brand and wattage), and roughly how long are you running the lights each day?

Right, there are two problems here and they're both contributing to what you're seeing. First, your T8 Reptisun 10.0 is almost certainly depleted — T8 tubes lose around 30% of their UVB output within six months even if they still glow, and at 18 months that bulb is functionally useless for meaningful UVB provision. Second, a T8 in a 4x2x2 enclosure doesn't throw UVB deep enough anyway — the gradient is too shallow. For a dragon his age, you actually want reliable, consistent UVB more than ever, not less. Senior dragons don't need a reduced photoperiod, but they do benefit from a slightly softer UVB index. I'd keep your photoperiod at 12-13 hours — that's fine. What's his basking spot temperature currently, and where exactly is the UVB tube positioned relative to where he basks?

That basking temperature is solid, so the heat side is well managed. The fact that he's moving away from the basking spot more often is a classic sign of UVB discomfort — counterintuitive, but when UVB output degrades unevenly or flickers at end-of-life, some dragons avoid the area altogether. The fix here is straightforward: switch to an Arcadia T5 HO 6% Forest UVB tube in a matching T5 HO reflector kit. The 6% (rather than the 12% he'd need as a juvenile or if wild-caught) is ideal for a senior captive-bred dragon — it provides a gentle, consistent Ferguson Zone 2-3 exposure without the intensity that can stress an older animal whose activity levels are naturally declining. The T5 format will give you proper UVB depth across the full 4-foot enclosure, reaching him comfortably at 10-12 inches. I'd go with the Arcadia T5 HO Dragon Kit 39W 1.2m — it comes with the tube and reflector together, so nothing is mismatched, and the reflector doubles usable UVB. Replace it every 12 months regardless of whether it still lights up.

It's a really common assumption but it works the other way. UVB output is about index and distance, not just percentage number. A T5 HO 6% in a reflector at 10-12 inches actually delivers a UVI of roughly 2-3 at basking level — that's exactly where a bearded dragon should sit in Ferguson Zone 3. The 12% tube is designed for deeper enclosures or for dragons kept at greater distances from the light, and in your setup at that distance it would push him into Zone 4 territory, which is uncomfortably intense and could explain exactly why he's avoiding the basking spot if that were the case. With the 6%, he'll bask more willingly because the light won't be aversive. Senior dragons still need full UVB — they just need it calibrated correctly, not cranked up.

Just the bulb and reflector for now — your basking temperatures are good, your photoperiod is right, and the enclosure size is appropriate. When you fit the new T5 kit, position the tube so it covers at least two-thirds of the vivarium length rather than the full length if you want to preserve a genuine UVB-free retreat at one end. Give him a week after the switch and I'd expect to see him basking more consistently and with more enthusiasm. If appetite and activity don't improve within two to three weeks of correct UVB, that's the point to get a vet check — a senior dragon who is genuinely slowing down may have early kidney changes or other age-related issues worth screening for, but lighting is always the first thing to rule out properly.